Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1
000
FXUS06 KWBC 231900
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU OCTOBER 23 2014

6-10 DAY OUTLOOK FOR OCT 29 - NOV 02, 2014

SIGNIFICANT UNCERTAINTY IS EVIDENT IN THE MODEL FORECASTS OVER ALASKA AND THE
NORTH PACIFIC EVEN AT RELATIVELY EARLY LEAD TIMES. BY THE 6-10 DAY PERIOD,
THERE IS POOR AGREEMENT AMONG MODEL ENSEMBLES AND DETERMINISTIC SOLUTIONS, BOTH
IN PHASE AND AMPLITUDE OF THE PREDICTED LONG WAVES. LARGE DIFFERENCES IN
PREDICTED CIRCULATION PATTERNS ARE FAIRLY COMMON IN AUTUMN, AS THE WESTERLIES
STRENGTHEN AND SHIFT SOUTH, AND AS WESTERN PACIFIC TYPHOONS GET CAUGHT UP INTO
THE MID-LATITUDE CIRCULATION WELL UPSTREAM OF THE U.S. IT IS VERY DIFFICULT TO
PREDICT THE TIMING AND AMPLITUDE OF INDIVIDUAL SHORT WAVES EMBEDDED WITHIN THE
MEAN FLOW. CONSIDERING THIS, SIGNIFICANT MODEL DIFFERENCES BETWEEN TODAY`S RUNS
AND YESTERDAY`S RUNS, AND MAINTAINING REASONABLE CONTINUITY WITH YESTERDAY`S
FORECAST, A LOW-AMPLITUDE FORECAST FLOW PATTERN IS THOUGHT TO BE APPROPRIATE IN
THIS CASE. SOMEWHAT HIGHER WEIGHTS IN THE OFFICIAL HEIGHT BLEND WERE GIVEN TO
THE 0Z ECMWF ENSEMBLE MEAN AND THE 6Z GFS ENSEMBLE MEAN, WHICH HAVE PROVIDED
SUPERIOR ANOMALY CORRELATION SCORES DURING THE PAST TWO MONTHS. THE OFFICIAL
HEIGHT FORECAST FAVORS A WEAK TROUGH OFF THE WEST COAST, A WEAK TROUGH OVER THE
OHIO VALLEY, AND A WEAK RIDGE OVER THE WEST-CENTRAL CONUS. IN ALASKA, CYCLONIC
CURVATURE IS GENERALLY FAVORED OVER THE NORTHERN PORTION OF THE STATE, AND
ANTICYCLONIC CURVATURE IS GENERALLY FAVORED OVER SOUTHERN AREAS OF THE STATE.

THE MOSTLY ZONAL UPPER LEVEL FLOW OVER THE CONUS LEADS TO ELEVATED CHANCES FOR
ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE NATION. THE 500-HPA TROUGH EXPECTED
NEAR THE WEST COAST INCREASES THE CHANCES FOR NEAR-NORMAL TEMPERATURES FROM THE
PACIFIC NORTHWEST TO THE NORTHERN ROCKIES, EXTENDING TO THE UPPER MISSISSIPPI
VALLEY. MOST OF ALASKA IS EXPECTED TO BE DOMINATED BY SOUTHWESTERLY FLOW, WHICH
FAVORS ABOVE-NORMAL TEMPERATURES EXCEPT FOR THE ALASKA PANHANDLE, WHERE
NORTHERLY UPPER LEVEL FLOW ALLOWS COOLER AIR FROM THE NORTH INTO THE REGION.

SOUTHWEST 500-HPA FLOW OVER MOST OF ALASKA FAVORS ABOVE-MEDIAN PRECIPITATION,
WHILE BELOW-MEDIAN PRECIPITATION IS FAVORED IN FAR SOUTHEASTERN ALASKA AND THE
PANHANDLE, UNDER NORTHERLY ANOMALOUS FLOW. TROUGHING NEAR THE WEST COAST AND
THE ANTICIPATION OF AN ENHANCED PACIFIC JET STREAM FAVORS ABOVE-MEDIAN
PRECIPITATION FROM THE PACIFIC NORTHWEST AND THE NORTHERN HALF OF CALIFORNIA TO
THE GREAT LAKES REGION. THE PRECIPITATION FORECAST FOR CALIFORNIA IS BASED MORE
HEAVILY ON THE DETERMINISTIC ECMWF SOLUTION, WHICH IS FAVORED OVER THE GFS AT
SHORTER TIME RANGES. IF THE GFS IS CORRECT, THE FAVORED AREA OF ABOVE-MEDIAN
PRECIPITATION WOULD BE RESTRICTED TO FAR NORTHERN CALIFORNIA. BELOW-MEDIAN
PRECIPITATION IS LIKELY FROM THE SOUTHWEST EASTWARD ACROSS THE SOUTHERN AND
CENTRAL PLAINS TO THE CENTRAL GULF COAST REGION, DUE TO THE EXPECTED INFLUENCE
OF LOW-LEVEL HIGH PRESSURE. ABOVE-MEDIAN PRECIPITATION IS ALSO FAVORED OVER THE
FLORIDA PENINSULA, DUE TO STALLED FRONTS OR PERHAPS TROPICAL MOISTURE FROM THE
YUCATAN REGION.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 30% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 40%
OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 20% OF TODAY`S 0Z
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8


MODEL OF THE DAY: TODAY`S 0Z EUROPEAN ENSEMBLE MEAN

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: WELL BELOW AVERAGE, 1 OUT OF 5,
DUE TO POOR AGREEMENT BETWEEN CANADIAN, ECMWF, AND GFS ENSEMBLE MEANS, AND THE
DETERMINISTIC SOLUTIONS FROM THE ECMWF AND GFS MODELS.

8-14 DAY OUTLOOK FOR OCT 31 - NOV 06, 2014

THE WEEK-2 FORECAST CIRCULATION PATTERN IS ALSO VERY UNCERTAIN OVER THE
PACIFIC-NORTH AMERICA REGION, AS IT WAS DURING THE 6-10 DAY PERIOD. THE 0Z
ECMWF ENSEMBLE MEAN SOLUTION DEPICTS A DEEPER TROUGH ACROSS THE FAR WEST, WITH
SOUTHWEST FLOW AHEAD OF IT, ACROSS NEARLY ALL OF THE CONUS. HOWEVER, THE OTHER
ENSEMBLE MEAN SOLUTIONS PREDICT A ZONAL PATTERN ACROSS THE CONUS. THE
DETERMINISTIC 0Z AND 6Z GFS RUNS ANTICIPATE AN AMPLIFIED WAVE PATTERN, WITH
DEEP TROUGHS OVER THE FAR EASTERN PACIFIC AND NEAR THE ATLANTIC SEABOARD, AND A
RIDGE OVER THE WEST-CENTRAL STATES. ONCE AGAIN, WITH SUCH WIDELY VARYING
500-HPA HEIGHTS, AND SURFACE TEMPERATURE AND PRECIPITATION PATTERNS DEPICTED
TODAY FROM ALL THE MODELS AND TOOLS, IT WAS DECIDED TO LEAN SLIGHTLY TOWARDS
THE 0Z ECMWF ENSEMBLE MEAN 2-METER TEMPERATURES, GO WITH A LOW-AMPLITUDE
PATTERN, AND MAINTAIN SUBSTANTIAL CONTINUITY WITH YESTERDAY`S OFFICIAL WEEK-2
FORECAST. MAINTAINING CONTINUITY IN THE FORECAST EFFECTIVELY PLACES MORE WEIGHT
ON THE ENSEMBLE MEMBERS THAT ARE CONSISTENT WITH YESTERDAY`S RUNS, WHICH IS
REASONABLE GIVEN THE WIDELY VARYING GUIDANCE TODAY.

THE WEEK-2 TEMPERATURE AND PRECIPITATION PATTERNS ARE SIMILAR TO THOSE FOR THE
6-10 DAY PERIOD.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 30% OF TODAY`S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 50% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON
DAY 11, AND 20% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: WELL BELOW AVERAGE, 1 OUT OF 5,
DUE TO LARGE DIFFERENCES IN THE PREDICTED HEIGHTS, AND SURFACE TEMPERATURE AND
PRECIPITATION PATTERNS.


FORECASTER: ANTHONY ARTUSA

NOTES:


AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES.
IN THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT
ISSUED.

THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS
THE SAME AS THAT IN THE TABLES: A-ABOVE   N-NEAR NORMAL   B-BELOW

THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER
(ORANGE, "A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL AVERAGE VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "F").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING
WETTER (GREEN, "A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL MEDIAN VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "INCHES").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL
BE A GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY
EVEN A NORMAL (I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY
SEASONS.  IN SUCH CASES A FORECAST OF NEAR NORMAL IS EFFECTIVELY A
FORECAST OF LITTLE OR NO PRECIPITATION.

THE CLIMATE PREDICTION CENTER USES 1981-2010 BASE PERIOD MEANS FOR
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN
THE CLIMATE OUTLOOKS.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON
NOVEMBER 20

ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
20051028 - 19541019 - 19841010 - 19641101 - 19831103


ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
20051027 - 19841009 - 19541018 - 19621002 - 19831102


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 29 - NOV 02, 2014

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      N    A     NRN CALIF   A    A
SRN CALIF   A    N     IDAHO       A    A     NEVADA      A    A
W MONTANA   N    A     E MONTANA   N    A     WYOMING     A    N
UTAH        A    N     ARIZONA     A    B     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    N    A     S DAKOTA    A    N
NEBRASKA    A    N     KANSAS      A    B     OKLAHOMA    A    B
N TEXAS     A    B     S TEXAS     A    B     W TEXAS     A    B
MINNESOTA   N    A     IOWA        N    N     MISSOURI    A    B
ARKANSAS    A    B     LOUISIANA   A    B     WISCONSIN   N    A
ILLINOIS    N    N     MISSISSIPPI A    B     MICHIGAN    N    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    N
TENNESSEE   A    N     ALABAMA     A    B     NEW YORK    A    A
VERMONT     A    N     NEW HAMP    A    N     MAINE       A    N
MASS        A    N     CONN        A    N     RHODE IS    A    N
PENN        A    A     NEW JERSEY  A    N     W VIRGINIA  A    N
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    A     AK N SLOPE  A    A
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  A    A
AK S INT    A    A     AK SO COAST A    N     AK PNHDL    B    B



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 31 - NOV 06, 2014

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      N    A     NRN CALIF   N    N
SRN CALIF   N    B     IDAHO       N    A     NEVADA      N    N
W MONTANA   N    A     E MONTANA   N    A     WYOMING     A    A
UTAH        A    N     ARIZONA     A    B     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    N    A     S DAKOTA    A    A
NEBRASKA    A    N     KANSAS      A    B     OKLAHOMA    A    B
N TEXAS     A    B     S TEXAS     A    B     W TEXAS     A    B
MINNESOTA   A    A     IOWA        A    N     MISSOURI    A    N
ARKANSAS    A    B     LOUISIANA   A    B     WISCONSIN   A    A
ILLINOIS    A    N     MISSISSIPPI A    B     MICHIGAN    A    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    N
TENNESSEE   A    N     ALABAMA     A    B     NEW YORK    A    A
VERMONT     A    N     NEW HAMP    A    N     MAINE       A    N
MASS        A    N     CONN        A    N     RHODE IS    A    N
PENN        A    A     NEW JERSEY  A    N     W VIRGINIA  A    N
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    A     AK N SLOPE  A    A
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  A    A
AK S INT    A    N     AK SO COAST A    N     AK PNHDL    N    B

                           LEGEND
TEMPS WITH RESPECT TO NORMAL     PCPN WITH RESPECT TO MEDIAN
A - ABOVE   N  - NEAR NORMAL     A - ABOVE   N - NEAR MEDIAN
B - BELOW                        B - BELOW

THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.

FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.